The potential benefits of high and low carotenoid-rich fruits and vegetables on preserving skeletal muscle mass in overweight/obese older adults when placed on a weight loss diet.

This is intended to be a 12-week randomized control trial in older adults >60 years. After a 1-week run-in period, participants will be randomly allocated to receive either: 1. A 12 week prescribed and individualized energy restricted diet to promote weight loss involving high carotenoid fruits and vegetables and extra-virgin olive oil; OR 2. A 12 week prescribed and individualized energy restricted diet to promote weight loss and low carotenoid fruits and vegetables, without extra-virgin olive oil During the one week run-in period (occurring after baseline) participants will be instructed to consume 100% of their habitual dietary intake before commencing the diet. The intervention diets are isocaloric (matched for energy and macronutrient distribution) with energy intake restricted by 30% of estimated requirements using the Mifflin equation. Diets are presented in the form of a checklist and are designed using energy bands ranging from 5000-8000KJ. Depending on the energy restriction, participants will be required to consume 225-375g high or low carotenoid vegetables per day. Specific examples of high carotenoid vegetables include, orange, red or yellow fruits and vegetables in addition to dark green leafy vegetables. Despite the two diets being matched for energy and macronutrient distribution, the composition of dietary fat will differ. Participants randomized to receive high carotenoid fruits and vegetables will also be prescribed olive oil. Prescription of the oil will depend on the energy restriction, however this will range from 40-70ml per day. Participants randomized to receive low carotenoid fruits and vegetables will be prescribed an alternative oil (Rice Bran or Canola oil). Irrespective of which group participants are allocated, all participants will receive a fortnightly fruit and vegetable hamper that reflects the types of fruits and vegetables they are required to consume. Participants randomized to the high-carotenoid fruits and vegetables, plus extra-virgin olive oil group will receive the olive oil throughout the duration of the study. All other food(s) allocated in the diet is o be provided by the participant. Throughout the 12-week intervention, participants will receive fortnightly (individual) dietary counselling sessions by an Accredited Practising Dietitian (APD). Each of these sessions will run for approximately 30 minutes in duration and will be used to assess compliance of the dietary protocol. During each session, the dietary protocol will be adjusted (scaled up or down) whenever required, depending on the rate of weight loss and/or weight maintenance.